Modified organic coating with polypyrrole and ZIF-67 decorated graphene oxide fillers for sustainable corrosion protection

Sustainable corrosion protective coatings are essential for industrial applications. Herein, graphene oxide (GO) was successfully decorated with ZIF-67 nanoparticles to form ZIF-67/GO (ZG) hybrids, which were employed as nanofillers for the dispersed carbon nanotube enhanced waterborne acrylic epoxy coating (DCE). The electrodeposited polypyrrole (PPY) film was then electrodeposited on the coating layer, resulting in a new anticorrosive coating (ZG/DCE/P) with self-healing functionality. The properties of ZG/DCE/P coating and PPY-free ZG/DCE coating were characterized in terms of morphology and microstructural properties, as well as the anticorrosion behavior. Compared to ZG/DCE coating, the composite ZG/DCE/P coating presented a substantial enhancement in the corrosion resistance, and the corrosion protection ability of this coating system were found to remain stable up to 30 days. The durable anticorrosion performance of the ZG/DCE/P coating stems from the synergistic effect of passive/active corrosion resistance mechanisms inherent in each coating component. The incorporation of ZG fillers increased the cross-linking density of the epoxy resin and prolonged the inward diffusion path of corrosive species; while the dense PPY layer not only acted as a barrier but also slowed the premature loss of corrosion inhibitors. The study provides new insights into the development of multifunctional anticorrosive coatings for engineering applications.